2015/21 – Eton (Queensland) – Uranium, Selenium, Hardness, Sodium, Chloride

Residents told uranium in the water



MACKAY Regional Council has informed Eton residents that uranium and selenium has been found in the town’s water supply.

In the letter delivered to residents on Monday it said recent monitoring has shown that uranium has been found in one of two bores supplying drinking water to the Eton community slightly above the ADWG health guideline level of 17 micrograms per litre.

Bore 2 levels ranged from 6.84 (0.00684mg/L) to 22.65 (0.02265mg/L).

Council said in the letter “this level is still below World Health Organisation (WHO) guidelines of 30 (0.030mg/L) but this bore has now been turned off”.

The remaining bore has levels of uranium that are below the ADWG guideline level.

The reported values for Bore 1 ranged from 6.98 (0.00698mg/L) to 14.33 (0.01433mg/L).

The level of radioactivity has also been measured in the two bores at Eton and both were found to be below the health screening levels in the ADWG.

Under the heading in the letter ‘selenium in drinking water supply at Eton’ it states “monitoring has shown that the level of selenium in the drinking water supplied to the township of Eton has varied over time”.

However, under the current water supply arrangements for Eton, the level of selenium slightly exceeds the current ADWG guideline level of 10 micrograms per litre (0.010mg/L), the letter says.

Reported values varied from 8.96 (0.00896mg/L) to 12.933 (0.012933mg/L).

Eton water is safe to drink

The council has “moved quickly to isolate groundwater supplies at Eton” it says, after elevated levels of uranium were detected in one of the bores.

The amount of uranium detected slightly exceeded the acceptable level as outlined in the Australian Drinking Water Guidelines but was below World Health Organisation guidelines.

Engineering and Commercial Infrastructure director Jason Devitt said in a statement there was no risk to the community and the affected bore had been turned off.

“We have taken swift action to stop using the bore and issued letters to all residents to reassure them about the situation,” he said.

Under the ADWG, a health guideline value of 17 micrograms per litre for uranium has been set. The WHO guideline has a limit of 30 micrograms per litre set (0.030 mg/L)

Eton’s supply was found to be 21 micrograms per litre (0.021mg/L).

Council officers and Queensland Health staff will hold community information sessions in Eton over the next two days to answer any questions.

They will be held at Eton Primary School on Tuesday, November 8 from 2pm to 6pm and Wednesday, November 9 from 8am to noon.

Eton’s second groundwater bore remains operational with slightly elevated levels of selenium, which occurs naturally in groundwater supplies.

Mr Devitt said council was considering its long-term options for the Eton water supply.

Queensland Health public health physician, Dr Steven Donohue, said Eton residents should not be concerned about ill-effects from their drinking water.

“The Australian guidelines have very wide safety margins and the uranium and selenium levels detected in the Eton bore are only a minor exceedance,” Dr Donohue said.

“The guidelines are also based on a lifetime of exposure and assume that is the main source of water consumed,” he said.

“However, the reality is people drink water from a variety of sources, so their overall dose of uranium and selenium would probably be lower,” he said.

Uranium water saga continues to frustrate residents



AFTER more than four months of debates and monitoring, Eton residents are still upset and angry with Mackay Regional Council over the quality of their water.

As the council released its most recent results from the ongoing uranium and selenium testing of the community’s two bores, people were left wondering when there would be a solution.

On September 9 last year the council first detected elevated levels of uranium in one of the town’s bores.

The bore was immediately turned off and the town was entirely reliant on one remaining bore, which was discovered to have elevated levels of selenium.

While uranium levels were initially up to 22.65 micrograms per litre, which is above ADWG health guidelines, they were still below World Health Organisation (WHO) guidelines of 30 micrograms per litre.

Residents weren’t notified about the uranium until November when the council mailed letters to householders in the area.

The initial outrage led to several community meetings where residents raised their concerns with the council and negotiated a strategy to move forward; however, it has become apparent there was some confusion to what was agreed.

Although the council committed to regular ongoing monitoring of the two bores and to publish the results publicly on its website, Eton residents believed the results would also be sent to their community representative.

This has yet to happen and resident Chris Tancred said he was frustrated by the lack of communication.

“The last contact we had with council was a meeting in Sarina and that was late November,” Mr Tancred said.

“The council was supposed to provide information to Tracey Williams and they didn’t this time.

“I just wish the council were more transparent about what was going on.”

The council’s ongoing monitoring has found fairly consistent levels of uranium and selenium in both bores. A third monitoring bore was drilled close by and the council said initial results were positive.

As elevated uranium levels have only been discovered in one bore, the council’s director of engineering and commercial infrastructure Jason Devitt considered the source to be “naturally found” as there were no results of radioactivity.

He said despite varying levels of uranium across a number of bores reviewed in Eton, Queensland Health had not changed its advice that the water supply was safe to consume.

The council is continuing to investigate options for alternative water supplies for the area, but for Mr Tancred a solution can’t come soon enough.

“If you’ve ever tasted the water here it’s not fine,” he said.

“It stains the tiles, makes a mess of the showers and tastes terrible.

“I’ve gone to the extent of buying enough water tanks where I don’t have to use it because it’s just that bad.”

Mackay Drinking Water Quality Management Plan 2016/17

Uranium Parameter

Two ‘Eton Treated’ samples were taken on 27 July 2016. One sample was collected whilst Bore 1 only was being run (Eton Treated (Bore 1) sample). The second sample was collected whilst Bore 2 only was being run (Eton Treated (Bore 2) sample). The Eton Treated (Bore 1) sample returned a uranium result of 0.00787 mg/L. The Eton Treated (Bore 2) sample returned a uranium result of 0.0202 mg/L. The Eton Treated (Bore 2) sample uranium result exceeds the ADWG health
value of 0.017 mg/L. These samples were not collected as part of the standard drinking water quality monitoring program and were in fact collected as part of a DWQMP investigation into selenium at Eton (Regulator reference DWI-7-489-00034).

Internal re-analysis of the original sample returned a uranium concentration of 0.017883 mg/L. External re-analysis of the original sample (by ALS) returned a uranium concentration of 0.019 mg/L. Following identification of this exceedance extraction of water from Bore 2 ceased and weekly sampling from within the Eton water supply scheme was undertaken to test for uranium within the supply. A number of Department of Natural Resources and Water (DNRM)
monitoring bores within the area were also sampled.

Eton residents were kept informed of the issue, and a number of public meetings were held. Queensland Health and DEWS were consulted regarding the investigation.

Results of MRC’s investigation did not reveal elevated uranium levels in any of the DNRM bores, in the Eton water supply Bore 1 or in the new monitoring bore that was constructed in the vicinity of the bores supplying water to the Eton water supply scheme.

Sampling within the Eton water supply scheme did not reveal an elevated level of uranium once the extraction of water form Bore 2 ceased. Currently Bore 1 is keeping up with demand from the Eton township.

Uranium Eton Reticulation: 0.01211 mg/L (max), 0.00715 mg/L (av.)

Eton (Queensland) – Selenium

14/6/16 – 22/6/16: Level Detected: 11.78 μg/L and 12.00μg/L

2016/17: Eton (Queensland) – Selenium 0.0138mg/L (max), 0.01193mg/L (av.)

2017/18: Eton (Queensland) – Reticulation – Selenium 0.01264 (max), 0.01151mg/L (av.)

Sampling of the Eton reticulation system on the 28 June returned a selenium result of 8.957 μg/L, below the 10 μg/L ADWG health value.

Investigation into the selenium levels in the Eton water supply is continuing. It was determined that selenium is present in the Eton groundwater bores which are the raw water supply for the
Eton scheme. Regular sampling of the two Eton groundwater bores and the Eton WTP Treated sample point has continued since the non-compliance was identified. Council will continue
to liaise with the regulator and Queensland health on this issue.


“Based on health considerations, the concentration of selenium in drinking water should not
exceed 0.01 mg/L.

Selenium and selenium salts are widespread in the environment. Selenium is released from natural and human-made sources, with the main source being the burning of coal. Selenium is also a by-product of the processing of sulfide ores, chiefly in the copper refining industry.

The major use of selenium is in the manufacture of electronic components. It is used in several other industries, and selenium compounds are used in some insecticides, in hair shampoos as an anti-dandruff agent, and as a nutritional feed additive for poultry and livestock.

Selenium concentrations in source waters are generally very low and depend on local geochemistry, pH and the presence of iron salts. Concentrations in drinking water supplies overseas are generally below 0.01 mg/L but groundwater concentrations as high as 6 mg/L have been reported in the United States.”

Australian Drinking Water Guidelines 2011

Eton (Queensland) – Hardness

2016/17: Eton (Queensland) Hardness 434.31mg/L (max), 391.65mg/L (av.)

2017/18: Eton (Queensland) Hardness 447.02mg/L (max), 412.71mg/L (av.)

2016/17: Eton Pony Club (Queensland) Hardness 349.39mg/L (max), 291.97mg/L (av.)

2020/21: Eton Treated (Queensland) Hardness 281.1mg/L (max), 132.85mg/L (min)

2020/21: Eton Reticulation (Queensland) Hardness 232.8mg/L (max), 144.55mg/L (min)


“To minimise undesirable build‑up of scale in hot water systems, total hardness (as calcium
carbonate) in drinking water should not exceed 200 mg/L.

Hard water requires more soap than soft water to obtain a lather. It can also cause scale to form on hot water pipes and fittings. Hardness is caused primarily by the presence of calcium and magnesium ions, although other cations such as strontium, iron, manganese and barium can also contribute.” Australian Drinking Water Guidelines 2011

Eton (Qld) – Chloride

2020/21: Eton Reticulation (Qld) Chloride 387.7mg/L (max), 139mg/L (min)

“Chloride is present in natural waters from the dissolution of salt deposits, and contamination from effluent disposal. Sodium chloride is widely used in the production of industrial chemicals such as caustic soda, chlorine, and sodium chlorite and hypochlorite. Potassium chloride is used in the production of fertilisers.

The taste threshold of chloride in water is dependent on the associated cation but is in the range 200–300 mg/L. The chloride content of water can affect corrosion of pipes and fittings. It can also affect the solubility of metal ions.

In surface water, the concentration of chloride is usually less than 100 mg/L and frequently below 10 mg/L. Groundwater can have higher concentrations, particularly if there is salt water intrusion.

Based on aesthetic considerations, the chloride concentration in drinking water should not exceed 250 mg/L.

No health-based guideline value is proposed for chloride.” 2011 Australian Drinking Water Guidelines

Eton (Qld) – Sodium

2020/21: Eton Treated (Sodium) 306.1mg/L (max), 152.2mg/L (min)

“Based on aesthetic considerations (taste), the concentration of sodium in drinking water
should not exceed 180 mg/L….The sodium ion is widespread in water due to the high solubility of sodium salts and the abundance of mineral deposits. Near coastal areas, windborne sea spray can make an important contribution either by fallout onto land surfaces where it can drain to drinking water sources, or from washout by rain. Apart from saline intrusion and natural contamination, water treatment chemicals, domestic water softeners and
sewage effluent can contribute to the sodium content of drinking water.” ADWG 2011